Ultrasonic degradation of nitrosodipropylamine (NDPA) and nitrosodibutylamine (NDBA) in water

Nitrosodipropylamine (NDPA) and nitrosodibutylamine (NDBA), two highly toxics and carcinogenic disinfection by-products, cannot be efficiently removed by conventional water treatment processes, while the ultrasound treatment was developed as a promising alternative. In this work, nitrosodipropylamine (NDPA) and nitrosodibutylamine (NDBA) are degraded by ultrasound treatment. Greater than 99% of NDPA and NDBA mixing solution could be decomposed within 60 min at neutral pH under optimal ultrasound power and frequency settings of 100 W and 600 kHz, respectively. Free radical reactions (OH•) played a significant role and the reaction sites were predominately at the bubble interface. The degradation of both NDPA and NDBA exhibited pseudo-first-order degradation kinetics, and the rate constant k_app was influenced by a number of factors including ultrasonic frequency, power, initial concentration, initial pH, various anions and cations frequently present in drinking water, hydroxyl radical scavengers, and water matrices, especially the promoting effect of various anions and cations and water matrices. The results of this study suggest the potential for ultrasound treatment as a method for removing NAms from water.

Role of various factors affecting the photochemical treatment of N-nitrosamines related to CO2 capture

Post-combustion CO₂ capture using amine solvents is the most feasible method of reducing anthropogenic CO₂ emissions, which are the largest contributor to global warming. The formation of carcinogenic N-nitrosamines (i.e. by-products) can hinder the industrial application of this technology. In this study, the effects of direct UV photolysis (N-nitrosamine concentration and amines) and advanced oxidation processes (UV/H₂O₂ and UV/O₃) on the three specific N-nitrosamines that are commonplace in amine-based CO₂ capture (i.e. N-nitrosodiethylamine (NDEA), N-nitrosodiethanolamine (NDELA), and N-nitrosomorpholine (NMOR)) were examined. A significant decrease in the photodegradation rate constants was observed for NDEA (1.02 × 10⁰ to 2.94 × 10^-1 min^-1), NDELA (1.52 × 10⁰ to 3.32 × 10^-1 min^-1), and NMOR (1.93 × 10⁰ to 2.20 × 10^-1 min^-1) as their concentrations increased within 1-50 mg/L. This is the first report of a significant increase in the degradation rate constants of N-nitrosamine with an increase in amine concentrations (i.e. monoethanolamine, diethanolamine, and morpholine) within 10-200 mM. The photodegradation rate constants increased as the molar ratio of H₂O₂ to N-nitrosamine increased to 20, but then decreased at molar ratios beyond this. O₃ had a negligible effect on the photodegradation of N-nitrosamines.

Role of absorber and desorber units and operational conditions for N-nitrosamine formation during amine-based carbon capture

The formation of carcinogenic N-nitrosamines from reactions between solvent amines and flue gas NO_x is an important concern for the application of amine-based processes to capture CO₂ post-combustion. Using an advanced test rig with interconnected absorber and desorber units, we evaluated the importance for N-nitrosamine formation of the desorber relative to the absorber, and any synergism between the two units. Variations in desorber temperature and in flue gas composition indicated that N-nitrosamine formation from fresh monoethanolamine (MEA) occurred predominantly in the absorber. N-nitrosamine formation was driven by high NO₂ and O₂ flue gas concentrations, although NO also contributed. In contrast, N-nitrosamine formation from piperazine (PZ) was driven by reactions with nitrite in the heated desorber, and accelerated concurrent with nitrite accumulation. A complementary experiment simulating aged MEA solvent (high nitrite, 1.5% sarcosine as a proxy of secondary amine degradation products) suggested the desorber becomes an order of magnitude more important than the absorber for N-nitrosamine formation. For fresh MEA solvent, increasing the desorber temperature from 110 °C to 130 °C promoted thermal decomposition of N-nitrosamines, reducing N-nitrosamine accumulation rates two-fold. Compared to the test rig, the prevailing practice of using separate absorber columns and autoclave-like treatments to mimic desorber units predicted the direction, but underestimated the magnitude of N-nitrosamine formation. Because N-nitrosamine accumulation rates are the net result of competing formation and thermal decomposition processes, use of continuously cycling test rigs may be necessary to understand the impacts of different operating conditions.

One size does not fit all: A NIDA CTN inspired model for community engaged cultural adaptation

The NIDA National Drug Abuse Treatment Clinical Trials Network (NIDA CTN) is devoted to the development of effective interventions for people who use substances across a variety of populations. When positive outcomes of a particular intervention do not generalize to other groups, adaptation may improve effectiveness for a different target group. However, currently limited information is available for involving community participation in cultural adaptation. The current paper illustrates the evolution of our methodology for community engaged cultural adaptation by describing a series of sexual health and substance use interventions. We highlight the transition from minimal community involvement (the Delphi process), to moderate community involvement (theater testing), to full community engagement in cultural adaptation. Ultimately, the results of these three projects led to the development of Community Collaborative Cultural Adaptation, a novel and concrete approach to cultural adaptation. This approach emphasizes the advantage of establishing academic/community partnerships for cultural adaptation to increase the effectiveness and sustainability of interventions.

Biomarkers of Exposure among Adult Smokeless Tobacco Users in the Population Assessment of Tobacco and Health Study (Wave 1, 2013-2014)

BACKGROUND

Monitoring population-level toxicant exposures from smokeless tobacco (SLT) use is important for assessing population health risks due to product use. In this study, we assessed tobacco biomarkers of exposure (BOE) among SLT users from the Wave 1 (2013-2014) of the Population Assessment of Tobacco and Health (PATH) Study.

METHODS

Urinary biospecimens were collected from adults ages 18 and older. Biomarkers of nicotine, tobacco-specific nitrosamines (TSNA), polycyclic aromatic hydrocarbons (PAH), volatile organic compounds (VOC), metals, and inorganic arsenic were analyzed and reported among exclusive current established SLT users in comparison with exclusive current established cigarette smokers, dual SLT and cigarette users, and never tobacco users.

RESULTS

In general, SLT users (n = 448) have significantly higher concentrations of BOE to nicotine, TSNAs, and PAHs compared with never tobacco users; significant dose-response relationships between frequency of SLT use and biomarker concentrations were also reported among exclusive SLT daily users. Exclusive SLT daily users have higher geometric mean concentrations of total nicotine equivalent-2 (TNE2) and TSNAs than exclusive cigarette daily smokers. In contrast, geometric mean concentrations of PAHs and VOCs were substantially lower among exclusive SLT daily users than exclusive cigarette daily smokers.

CONCLUSIONS

Our study produced a comprehensive assessment of SLT product use and 52 biomarkers of tobacco exposure. Compared with cigarette smokers, SLT users experience greater concentrations of some tobacco toxicants, including nicotine and TSNAs.

IMPACT

Our data add information on the risk assessment of exposure to SLT-related toxicants. High levels of harmful constituents in SLT remain a health concern.

Plasminogen activator inhibitor-2 (PAI-2) overexpression supports bladder cancer development in PAI-1 knockout mice in N-butyl-N- (4-hydroxybutyl)-nitrosamine- induced bladder cancer mouse model

BACKGROUND

Accumulating evidence suggests that plasminogen activator inhibitor-1 (PAI-1) plays an important role in bladder tumorigenesis by regulating cell cycle. However, it remains unclear whether and how inhibition of PAI-1 suppresses bladder tumorigenesis.

METHODS

To elucidate the therapeutic effect of PAI-1 inhibition, we tested its tumorigenicity in PAI-1 knockout (KO) mice exposed to a known bladder carcinogen.

RESULTS

PAI-1 deficiency did not inhibit carcinogen-induced bladder cancer in mice although carcinogen-exposed wild type mice significantly increased PAI-1 levels in bladder tissue, plasma and urine. We found that PAI-1 KO mice exposed to carcinogen tended to upregulate protein C inhibitor (PAI-3), urokinase-type plasminogen activator (uPA) and tissue-type PA (tPA), and significantly increased PAI-2, suggesting a potential compensatory function of these molecules when PAI-1 is abrogated. Subsequent studies employing gene expression microarray using mouse bladder tissues followed by post hoc bioinformatics analysis and validation experiments by qPCR and IHC demonstrated that SERPING1 is further downregulated in PAI-1 KO mice exposed to BBN, suggesting that SERPING1 as a potential missing factor that regulate PAI-2 overexpression (compensation pathway).

CONCLUSIONS

These results indicate that serpin compensation pathway, specifically PAI-2 overexpression in this model, supports bladder cancer development when oncoprotein PAI-1 is deleted. Further investigations into PAI-1 are necessary in order to identify true potential targets for bladder cancer therapy.

New versatile zincic sorbent for tobacco specific nitrosamines and lead ion capture

New carbon-doped ferric zinc oxide sorbents were fabricated to capture the environment carcinogen tobacco specific nitrosamines (TSNA) efficiently in solution, following new adsorption model of electrostatic attraction instead of traditional geometric constraints. The influence of ferric content on the structure-property of the sorbents was systemically studied with XRD, N2 adsorption-desorption and SEM methods combined with the adsorption of TSNA in different solutions. New sorbent captured 99% of 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK) in simulated surface water and 40% of TSNA in the tobacco extract solution, more than activated carbon or zeolites. Ferric ZnO sorbent took about 15 min to reach the adsorption equilibrium in the NNK or Pb(Ⅱ) solution, faster than NaZSM-5 zeolite. Moreover, the adsorbed NNK on ferric ZnO sorbent decomposed at mild conditions for the first time, providing a new way to control environment pollution.

One representative water supply system in China with nitrosamine concern: Challenges and treatment strategies

Four sampling campaigns were conducted in two years to understand the fluctuation of N-Nitrosamines (NAs) and their precursors in one drinking water treatment plant (DWTP) in East China in different seasons. This water supply system has been facing several nitrosamine challenges related with source water, including the switch of water source, high concentration of ammonium, formed NAs and NA formation potential (FP) in source water. Besides, the use of ozonation in the DWTP and chloramination in networks will increase the NDMA concentration in tap water. To address these challenges, the bio-pretreatment was applied in this DWTP to decrease the concentration of ammonium and NAs. The following biological activated carbon (BAC) will neutralize the nitrosamine increase brought by ozonation. The use of free chlorine in disinfection process will also decrease the NDMA formation compared with chloramination. The results will benefit other cities in China and other countries with similar impacted water sources.

N-Nitrosamine formation from chloramination of two common ionic liquids

Ionic liquids (ILs) are a class of solvents increasingly used as "green chemicals." Widespread applications of ILs have led to concerns about their accidental entry to the environment. ILs have been assessed for some environmental impacts; however, little has been done to characterize their potential impacts on drinking water if ILs accidentally enter surface water. IL cations are often aromatic or alkyl quaternary amines that resemble structures of previously confirmed N-nitrosamine (NA) precursors. Therefore, this study has evaluated two common ILs, 1-ethyl-3-methylimidazolium bromide (EMImBr) and 1-ethyl-1-methylpyrrolidinium bromide (EMPyrBr), for their NA formation potential. Each IL species was reacted with pre-formed monochloramine under various laboratory conditions. The reaction mixtures were extracted using liquid-liquid extraction and analyzed for NAs using high performance liquid chromatography tandem mass spectrometry. At low concentration of IL (250 μmol/L), the yields of NAs (NMEA or NPyr) increased with increasing doses of monochloramine from both IL species. The total NA yield was as high as 2.5 ± 0.3 ng/mg from EMImBr, and as high as 8.6 ± 0.8 ng/mg from EMPyrBr. At high concentration of IL (5 mmol/L), the NA yield reached a maximum at 2.5 mmol/L NH₂Cl, and then decreased with subsequent increases in the reactant concentrations, demonstrating ILs' solvent effects. This study re-emphasizes the importance of preventing discharge of ILs to water bodies to prevent secondary impacts on drinking water.

Occurrence of N-Nitrosamines in the Pearl River delta of China: Characterization and evaluation of different sources

N-nitrosamines in water have drawn significant concerns for the health of water consumers due to their carcinogenic properties. N-nitrosamines are formed during disinfection of wastewater as well as different industrial and agricultural processes. This study characterized the N-nitrosamines compositions in eleven different wastewaters in the Pearl River Delta (PRD) in Southeast China, and the spatial distributions and the abundances of N-nitrosamines in the Pearl River water were detected. The results indicated that five N-nitrosamines species, including N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR) and N-nitrosodibutylamine (NDBA) were found in the industrial wastewater samples in the PRD. Remarkably high concentrations of NDMA (up to 4000 ng/L) were found in the wastewaters from the textile printing and dyeing as well as the electroplating, whereas NDMA, NDEA and NMOR were detected in the domestic wastewaters at concentrations lower than 15 ng/L. Moreover, we found that certain treatment processes for the electroplating wastewater could form a significant amount of NDMA, NPYR and NMOR. Analyses of the Pearl River water samples showed occurrences of different N-nitrosamines species, including NDMA (5.7 ng/L), NDEA (1.7 ng/L), NPYR (2.2 ng/L), NMOR (2.2 ng/L) and NDBA (4.9 ng/L). The abundances of N-nitrosamines species varied spatially due to the inputs from the different sources. Thus, our study provides unique and valuable information for occurrences, abundances and source characteristics of N-nitrosamines in the PRD.

Density function theory (DFT) calculated infrared absorption spectra for nitrosamines

Absorption spectra within the infrared (IR) range of frequencies for nitrosamines in water are calculated using density function theory (DFT). Calculated in this study, are the IR spectra of C₂H₆N₂O, C₄H₁₀N₂O, C₆H₁₄N₂O, C₄H₈N₂O, C₃H₈N₂O, and C₈H₁₈N₂O. DFT calculated absorption spectra corresponding to vibration excited states of these molecules in continuous water background can be correlated with additional information obtained from laboratory measurements. The DFT software Gaussian was used for the calculations of excited states presented here. This case study provides proof of concept, viz., that such DFT calculated spectra can be used for their practical detection in environmental samples. Thus, DFT calculated spectra may be used to construct templates, for spectral-feature comparison, and thus detection of spectral-signature features associated with target materials.

N-nitrosomorpholine behavior in sewage treatment plants and urban rivers

The seasonal and diurnal patterns of N-nitrosomorpholine (NMOR) and its formation potential (NMOR FP) were examined with water samples taken from five outlets of four sewage treatment plants (STPs), seven main stream sites, and five tributary sites in the Yodo River basin. STPs were shown to be the main sources of downstream NMOR load. The highest NMOR levels were found in the discharge from one STP (26.4-171 ng/L). Continuous sequential samplings over a period of 24 h at this STP revealed that NMOR flux at the influent point fluctuated in both summer (0.4-3.2 g/h) and winter (0.3-5.4 g/h), while it was steady in the effluent. In addition, levels of NMOR remained stable during the biological treatment and disinfection processes. The present research demonstrated that NMOR could be formed from morpholine (MOR) in raw sewage treated by this STP, with a possible mechanism being formaldehyde-catalyzed nitrosation of MOR by nitrites, prior to raw sewage entering the STP. This implies that the NMOR detected here might not be a disinfection byproduct per se under low-chlorine disinfection (around 1.0 mg/L), but is primarily a contaminant that is difficult to remove during sewage treatment. NMOR attenuated significantly in the rivers in the daytime with production of MOR, but persisted during nights, which demonstrated the importance of monitoring NMOR levels in the water environment during periods of low UV intensity, especially nights.

Carcinogenic risk of N-Nitrosamines in Shanghai Drinking Water: Indications for the Use of Ozone Pretreatment

N-Nitrosamines are drinking water disinfection byproducts that pose a high carcinogenic risk. We hypothesized that raw water treatment processes influence the types and concentrations of nitrosamines in drinking water, thereby posing differential health risks. We compared the finished water of two water treatment plants (WTP-A, WTP-B) serving Shanghai, China. Both plants use the Qingcaosha reservoir as a water source to generate drinking water with conventional but distinct treatment processes, namely preoxidation with sodium hypochlorite (WTP-A) vs ozone (WTP-B). Average nitrosamine concentrations, especially that of the probable human carcinogen (2A) N-nitrosodimethylamine, were higher in finished (drinking) water from WTP-A (35.83 ng/L) than from WTP-B (5.07 ng/L). Other differences in mean nitrosamines in drinking water included N-nitrosodipropylamine (42.62 ng/L) and N-nitrosomethylethylamine (26.73 ng/L) in WTP-A in contrast to N-nitrosodiethylamine (7.26 ng/L) and N-nitrosopyrrolidine (59.12 ng/L) in WTP-B. The estimated adult cancer risk from exposure to mixed nitrosamines was 1.83 times higher from WTP-A than from WTP-B drinking water. Children exposed to nitrosamines had a significantly higher cancer risk than adults ( p < 0.05). Disease burden exceeded 10⁶ person-years. Taken together, these data suggest that use of ozone in the preoxidation step can reduce nitrosamine formation in drinking water and thereby lower the population cancer health risk.

Uncovering a unique approach for damaged DNA replication: A computational investigation of a mutagenic tobacco-derived thymine lesion

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone is a potent nicotine carcinogen that leads to many DNA lesions, the most persistent being the O2-[4-oxo-4-(3-pyridyl)butyl]thymine adduct (POB-T). Although the experimental mutagenic profile for the minor groove POB-T lesion has been previously reported, the findings are puzzling in terms of the human polymerases involved. Specifically, while pol κ typically replicates minor groove adducts, in vivo studies indicate pol η replicates POB-T despite being known for processing major groove adducts. Our multiscale modeling approach reveals that the canonical (anti) glycosidic orientation of POB-T can fit in the pol κ active site, but only a unique (syn) POB-T conformation is accommodated by pol η. These distinct binding orientations rationalize the differential in vitro mutagenic spectra based on the preferential stabilization of dGTP and dTTP opposite the lesion for pol κ and η, respectively. Overall, by uncovering the first evidence for the replication of a damaged pyrimidine in the syn glycosidic orientation, the current work provides the insight necessary to clarify a discrepancy in the DNA replication literature, expand the biological role of the critical human pol η, and understand the mutational signature in human cancers associated with tobacco exposure.

Genotoxicity assay and potential byproduct identification during different UV-based water treatment processes

Formation of genotoxic byproducts during different ultraviolet (UV) -related water/wastewater treatment processes (including medium pressure (MP) UV oxidation, LP UV oxidation, chlorination, biological activated carbon (BAC) treatment, H₂O₂ oxidation, and two or more combined processes) was investigated by Ames fluctuation test using Salmonella strains TA98 and TA100 with and without rat liver enzyme extract S9. Byproducts responsible for genotoxicity were identified. The results showed that MP UV can induce mutagenicity and LP UV treatment does not induce mutagenicity. H₂O₂ oxidation could degrade part of genotoxic compounds. Compared with chlorination, BAC treatment is more effective in removing genotoxicity. Mutagenicity was found mostly in samples tested with TA100 instead of TA98, especially with TA100 without S9, indicating that guanosine and/or cytosine adducts contribute to mutation or toxicological effects in MP UV treated samples. Potential genotoxic byproducts were selected, most of which were nitrogenous organic compounds with more than 10 carbon atoms. Nitrosamines and histidine were excluded from potential genotoxic candidates. The results could contribute to evaluation of mutagenicity of various UV-based water treatment processes.

N-nitrosomorpholine in potable reuse

As potable reuse guidelines and regulations continue to develop, the presence of N-nitrosamines is a primary concern because of their associated health concerns. In this study, bench-, pilot-, and full-scale tests were conducted to focus on the occurrence and treatment of N-nitrosomorpholine (NMOR) in United States (U.S.) potable reuse systems. Out of twelve U.S. wastewater effluents collected, ambient NMOR was detected in eleven (average = 20 ± 18 ng/L); in contrast, only two of the thirteen surface water and stormwater samples had NMOR. Across all of these samples maximum formation potential by chloramination produced an average increase of 3.6 ± 1.8 ng/L. This result underscores the need to understand the sources of NMOR as it is not likely a disinfection byproduct and it is not known to be commercially produced within the U.S. At the pilot-scale, three potable reuse systems were evaluated for ambient NMOR with oxidation (i.e., chlorination and ozonation), biofiltration, and granular activated carbon (GAC). Both pre-oxidation and biofiltration were ineffective at mitigating NMOR during long-term pilot plant operation (at least eight-months). GAC adsorbers were the only pilot-scale treatment to remove NMOR; however, complete breakthrough occurred rapidly from <2000 to 10,000 bed volumes. For comparison, a full-scale reverse osmosis (RO) potable reuse system was monitored for a year and confirmed that RO effectively removes NMOR. Systematic bench-scale UV-advanced oxidation experiments were undertaken to assess the mitigation potential for NMOR. At a fluence dose of 325 ± 10 mJ/cm²_, UV alone degraded 90% of the NMOR present. The addition of 5 mg/L hydrogen peroxide did not significantly decrease the UV dose required for one-log removal. These data illustrate that efficient NMOR removal from potable reuse systems is limited to RO or UV treatment.

Update on thirdhand smoke: A comprehensive systematic review

OBJECTIVE

The objective of this study is to perform a comprehensive review of the literature about thirdhand smoke (THS).

METHODS

Systematic review of all aspects of THS. Standard methodological procedures were used to search the following databases through April 2018: MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science (WOS) in Indo-European languages. To identify published grey literature, the first 200 hits from Google Scholar™ were evaluated. Clinical trial databases, conference proceedings, and reference lists from the identified articles were also searched. Two unblinded review authors independently assessed trials for inclusion in the review. These same reviewers also extracted study data in accordance with PRISMA guidelines. The study protocol was registered with PROSPERO (CRD42018083619).

RESULTS

Sixty-eight articles were included in this systematic review. Of these, 28 analyzed the concentration of nicotine as a component of THS (the most commonly-used method to measure THS in those studies was chromatography, followed by the mass spectrometry), 21 evaluated the exposure and impact of THS on health (11 studies analyzed the effect of THS in cells [human and animal], 4 in animals, 1 in adults, and 5 in children), 16 investigated the beliefs, behaviours, and policies related to THS, and 3 evaluated other aspects such as THS in e-cigarettes or hookahs. In these 68 studies, THS was determined by measuring the following components: nicotine (30 studies), nitrosamines (17 studies) and cotinine (15 studies). The findings from most of these studies suggest a potential health impact of THS exposure (i.e.: cytotoxicity, metabolic alterations in metabolism, in glycemia; or cell structure; alterations in liver, lung, skin and behaviour in mice), and low awareness about the risks of THS among the general population.

CONCLUSIONS

Numerous specific biomarkers of THS were evaluated, with the most common being nicotine, nitrosamines, and cotinine. The most common method of preparing THS dust samples were cotton wipes, while chromatography, used alone or coupled with mass spectrometry, was the most common analytical technique. We have tried to establish common bases after reviewing all the current literature of the THS although, there is great heterogeneity between the studies and we have not always succeeded. The studies in this review demonstrate the harmful effects of THS on health in cells, in animal models, and in people including children. However, in people, the long-term effects remain unknown and more research is needed. These studies show that knowledge about THS and its potential harmful effects are poorly understood among the general population. For this reason, THS should receive greater emphasis in education and awareness policies.

Computational Insight into the Activation Mechanism of Carcinogenic N'-Nitrosonornicotine (NNN) Catalyzed by Cytochrome P450

Tobacco-specific N'-nitrosonornicotine (NNN), a genotoxic nitrosamine classified as Group 1 carcinogen, is also present in atmospheric particulate matter and has even been detected as a new disinfection byproduct in wastewaters. NNN generally requires metabolic activation by cytochrome P450 enzymes to exert its genotoxicity, but the respective biotransformation pathways have not been described in detail. In this work, we performed density functional theory (DFT) calculations to unravel possible NNN activation pathways including α-hydroxylation, β-hydroxylation, pyridine N-oxidation, and norcotinine formation. The results reveal an initial rate-determining H_α-atom abstraction step for α-hydroxylation, followed by an unexpected kinetic competition between denitrosation and OH rebound, leading to ( iso-)myosmine as a detoxified product and α-hydroxyNNNs as the precursor of carcinogenic diazohydroxides, respectively. Further detoxification routes are given by β-hydroxylation with relative high reaction barrier and N-oxidation with comparable barrier to the toxifying α-hydroxylation. Moreover, we show for the first time how norcotinine can be generated as a minor NNN metabolite that is formed from iso-myosmine through a unique porphyrin-assisted H atom 1,2-transfer mechanism. These results demonstrate that the carcinogenic potential of NNN is subject to a kinetic competition between activating and deactivating metabolic routes, and identify respective biomarkers to inform about the individual risk associated with NNN exposure.

Atmospheric Oxidation of Piperazine Initiated by ·Cl: Unexpected High Nitrosamine Yield

Chlorine radicals (·Cl) initiated amine oxidation plays an important role for the formation of carcinogenic nitrosamine in the atmosphere. Piperazine (PZ) is considered as a potential atmospheric pollutant since it is an alternative solvent to monoethanolamine (MEA), a benchmark solvent in a leading CO₂ capture technology. Here, we employed quantum chemical methods and kinetics modeling to investigate ·Cl-initiated atmospheric oxidation of PZ, particularly concerning the potential of PZ to form nitrosamine compared to MEA. Results showed that the ·Cl-initiated PZ reaction exclusively leads to N-center radicals (PZ-N) that mainly react with NO to produce nitrosamine in their further reaction with O₂/NO. Together with the PZ + ·OH reaction, the PZ-N yield from PZ oxidation is still lower than that of the corresponding MEA reactions. However, the nitrosamine yield of PZ is higher than the reported value for MEA when [NO] is <5 ppb, a concentration commonly encountered in a polluted urban atmosphere. The unexpected high nitrosamine yield from PZ compared to MEA results from a more favorable reaction of N-center radicals with NO compared to O₂. These findings show that the yield of N-center radicals cannot directly be used as a metric for the yield of the corresponding carcinogenic nitrosamine.

Regulation of toxic contents of smokeless tobacco products

Effective regulation of contents of tobacco products is one of the primary milestones to reduce negative health effects associated with the use of smokeless tobacco (SLT) products. As per the available sources, testing of some SLT products has been done on ad hoc basis, but there is a lack of comprehensive and periodic analysis of these products. In addition, the available results indicate huge variations among the levels of pH, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, N-nitrosonornicotine, benzo[a]pyrene, heavy metals and nicotine within different products as well as within different brands of the same product. This review was aimed to throw light on the variations and gaps in testing of SLT products and emphasize the need for strong policy regulation for monitoring the chemical constituents of these products.

Histology of Chemically Induced Mesotheliomas in Mrc-wistar Rats

Two peritoneal mesotheliomas were induced in rats during a carcinogenicity study of 1-nitroso-5,6-dihydrouracil (NO-DHU) injected intraperitoneally. A review of literature concerning experimental induction of such tumors indicated that they seldom produced with organic compounds and rarely occur spontaneously. In the present study, several reports of chemically induced mesotheliomas of the testes are analyzed and the diagnoses critically reviewed along with other differential diagnoses.

A Study on the Role of Compensatory Hyperplasia in Renal Carcinogenesis with Dimethylnitrosamine in the Rat

Two experiments of renal carcinogenesis with dimethylnitrosamine (DMN) are described. In experiment I, the carcinogenicity of a single neonatal injection of DMN was compared in 34 intact rats and in 38 rats right-nephrectomized at 8–10 weeks of age. A total of 37 tumor-bearing kidneys were seen: both tubular and anaplastic; tumor incidence and time of observation showed no significant differences between intact and nephrectomized animals. Liver tumors were seen in 38 of 72 rats. In experiment II, 64 adult rats were given DMN in the drinking water for 2 weeks at a concentration corresponding to half an effective dose: 20 rats were used as non-nephrectomized controls; the others were right nephrectomized either on the 7th - 8th day of treatment with DMN or 15 days prior to the beginning of the treatment with the carcinogen. In no case did unilateral nephrectomy have a modifying effect upon carcinogenesis. In nephrectomized rats nonneoplastic nephritic changes were more severe than in intact animals. The design of the present experiments is compared with that of previous studies on the role of either partial hepatectomy or unilateral nephrectomy in carcinogenesis.

Immunohistochemical Modifications of “B Cells” in Experimentally-induced Pancreatic Cancer — Correlation with Serum Insulin Values

In pancreatic ductal adenocarcinoma induced in the Syrian hamster by N-nitrosobis (2-oxopropyl) amine (Bop) B cells persisted with focal dispersion in the tumor zone. The localization of these varied depending on whether the animals had initial or long standing tumors. In the animals with initial tumors, immunohistochemical techniques indicated the B cells formed part of the tumoral glands and/or were intimately related to the cells of the walls of the tumor glands or present in the stroma. Insulin values were high in these animals. In the longer-developed tumors, insulin levels tended to be lower and although B cells were seen forming part of the tumor glands, those in the tumoral stroma were predominant.

Ruthenium Catalysts for the Reduction of N-Nitrosamine Water Contaminants

N-Nitrosamines have raised extensive concern due to their high toxicity and detection in treated wastewater and drinking water. Catalytic reduction is a promising alternative technology to treat N-nitrosamines, but to advance this technology pathway, there is a need to develop more-efficient and cost-effective catalysts. We have previously discovered that commercial catalysts containing ruthenium (Ru) are unexpectedly active in reducing nitrate. This study evaluated supported Ru activity for catalyzing reduction of N-nitrosamines. Experiments with N-nitrosodimethylamine (NDMA) show that contaminant is rapidly reduced on both commercial and in-house prepared Ru/Al₂O₃ catalysts, with the commercial material yielding an initial metal weight-normalized pseudo-first-order rate constant ( k₀) of 1103 ± 133 L·g_Ru^-1·h^-1 and an initial turnover frequency (TOF₀) of 58.0 ± 7.0 h^-1. NDMA is reduced to dimethylamine (DMA) and ammonia end-products, and a small amount of 1,1-dimethylhydrazine (UDMH) was detected as a transient intermediate. Experiment with a mixture of five N-nitrosamines spiked into tap water (1 μg L^-1 each) demonstrates that Ru catalysts are very effective in reducing a range of N-nitrosamine structures at environmentally relevant concentrations. Cost competitiveness and high catalytic activities with a range of contaminants provide a strong argument for developing Ru catalysts as part of the water purification and remediation toolbox.

Preventive Potential of Resveratrol in Carcinogen-Induced Rat Thyroid Tumorigenesis

Thyroid cancer (TC) is the most common endocrine malignancy without reliable preventive agent. Resveratrol possesses in vitro anti-TC activities; while its effect(s) on thyroid tumorigenesis remains unknown. This study aims to address this issue using DEN/MNU/DHPN-induced rat carcinogenesis model. 50 male Sprague-Dawley rats were separated into four groups as Group-1 (5 rats); normally fed; Group-2 (15 rats); DEN/MNU/DHPN treatment only; Group-3 (15 rats) and -4 (15 rats); DEN/MNU/DHPN treatment; followed by resveratrol intragastric (IG) injection and intraperitoneal (IP) injection; respectively; in two-day intervals for 30 weeks. The results revealed that the average resveratrol concentration in thyroid tissues was 1.278 ± 0.419 nmol/g in IG group and 1.752 ± 0.398 nmol/g in IP group. The final body weights of Group-3 and Group-4 were lighter than that (p > 0.05) of Group-1; but heavier than Group-2 (p < 0.05). TC-related lesions (hyperplasia and adenomas) were found in 53.3% of Group-2; 33.3% Group-3 and 26.7% Group-4. Lower serum carcino-embryonic antigen (CEA) and thyroglobulin (Tg) levels; down-regulated expression of IL-6 and cyclooxygenase-2 (COX-2); reduction of NF-κB/p65 nuclear translocation; and elevated IkBα expression were found in the thyroid tissues of Group-3 and Group-4 in comparison with that of Group-2. These results demonstrate that IG and IP administered resveratrol efficiently reduces the frequency and severity of DEN/MNU/DHPN-caused TC-related lesions and would be of values in thyroid tumor prevention.

Toxic compounds from tobacco in placenta samples analyzed by UPLC-QTOF-MS

Polycyclic aromatic hydrocarbons (PAHs), tobacco-specific nitrosamines (TSNAs) and aromatic amines are carcinogens present in cigarette smoke. These compounds are distributed in the human body and they could be transferred to the foetus during the pregnancy. Placenta is the main barrier to these toxic compounds and its study is the objective of this work. A method based on solid-phase extraction (SPE) with ultra-performance liquid chromatography-tandem quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS) has been examined and optimized for the analysis of 9 target analytes (4 tobacco-specific nitrosamines and some of their metabolites, 3 aromatic amines, nicotine and cotinine) in 26 placenta samples from smoking and non-smoking women. Limits of detection (LODs) were in the range of 3-27ng/g of placenta. Nicotine, cotinine, N-nitrosoanatabine (NAT) and 4-(methylnitrosamino)-1- (3-pyridyl)-1-butanone (NNK) metabolite, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) were detected in the placenta samples of smoking woman. Nicotine was detected in 3 out of 8 placentas from smoking women, always below the limit of quantification (88ng/g). This could be expected, as the half-life of nicotine in the body is limited to about 0.5-3h. Cotinine, the main metabolite from nicotine, was detected in all placentas from smoking women at concentrations between 17.2 and 61.8ng/g, reaching the highest values for those women that smoked the highest number of cigarettes. NAT and NNAL were detected in all placentas from smoking women, always below the limit of quantification (40ng/g and 33ng/g respectively).

Nitrosamines and Nitramines in Amine-Based Carbon Dioxide Capture Systems: Fundamentals, Engineering Implications, and Knowledge Gaps

Amine-based absorption is the primary contender for postcombustion CO₂ capture from fossil fuel-fired power plants. However, significant concerns have arisen regarding the formation and emission of toxic nitrosamine and nitramine byproducts from amine-based systems. This paper reviews the current knowledge regarding these byproducts in CO₂ capture systems. In the absorber, flue gas NO_x drives nitrosamine and nitramine formation after its dissolution into the amine solvent. The reaction mechanisms are reviewed based on CO₂ capture literature as well as biological and atmospheric chemistry studies. In the desorber, nitrosamines are formed under high temperatures by amines reacting with nitrite (a hydrolysis product of NO_x), but they can also thermally decompose following pseudo-first order kinetics. The effects of amine structure, primarily amine order, on nitrosamine formation and the corresponding mechanisms are discussed. Washwater units, although intended to control emissions from the absorber, can contribute to additional nitrosamine formation when accumulated amines react with residual NO_x. Nitramines are much less studied than nitrosamines in CO₂ capture systems. Mitigation strategies based on the reaction mechanisms in each unit of the CO₂ capture systems are reviewed. Lastly, we highlight research needs in clarifying reaction mechanisms, developing analytical methods for both liquid and gas phases, and integrating different units to quantitatively predict the accumulation and emission of nitrosamines and nitramines.

Assessment of genotoxicity amongst smokers, alcoholics, and tobacco chewers of North India using micronucleus assay and urinary 8-hydroxyl-2'-deoxyguanosine, as biomarkers

The main objective of the present study was to screen the genotoxicity caused by individual and combined habits of smoking, tobacco chewing, and alcohol consumption in human population of North India. Study recruited 67 male subjects aged 25 to 65 years. Buccal mucosal cells were subjected to micronucleus (MN) assay, and 8-hydroxyl-2-deoxyguanosine (8-OHdG) was estimated in their urine samples. Number and shape of the MN cells varied in the buccal epithelium of different groups. Maximum number of MN (0.47%) were found in tobacco chewers followed by smokers (0.45%) and alcoholics (0.44%) (P < 0.05). These results reciprocated the concentration of urinary 8-OHdG. Maximum value for 8-OHdG was also recorded in tobacco chewers (21.07 ± 5.51 mg/mg creatinine) followed by smokers (20.25 ± 3.96 mg/mg creatinine) and alcoholics (19.06 ± 3.41 mg/mg creatinine) (P < 0.05). Combined effects of these agents were found to be statistically different from individual effects. Carcinogenic compounds present in cigarette smoke, nitrosamines found in solid tobacco, and acetaldehyde, a metabolic product of alcohol, induce oxidative stress that manifests into genotoxicity. In conclusion, demographical differences occur in the genotoxicity caused by these three habits. MN assay and urinary 8-OHdG are simple, noninvasive, and reliable biomarkers of genotoxicity.

Zebrafish embryo toxicity of 15 chlorinated, brominated, and iodinated disinfection by-products

Disinfection to protect human health occurs at drinking water and wastewater facilities through application of non-selective oxidants including chlorine. Oxidants also transform organic material and form disinfection by-products (DBPs), many of which are halogenated and cyto- and genotoxic. Only a handful of assays have been used to compare DBP toxicity, and researchers are unsure which DBP(s) drive the increased cancer risk associated with drinking chlorinated water. The most extensive data set employs an in vitro model cell, Chinese hamster ovary cells. Traditionally, most DBP research focuses on the threat to human health, but the effects on aquatic species exposed to DBPs in wastewater effluents remain ill defined. We present the developmental toxicity for 15 DBPs and a chlorinated wastewater to a model aquatic vertebrate, zebrafish. Mono-halogenated DBPs followed the in vivo toxicity rank order: acetamides>acetic acids>acetonitriles~nitrosamines, which agrees well with previously published mammalian in vitro data. Di- and tri-halogenated acetonitriles were more toxic than their mono-halogenated analogues, and bromine- and iodine-substituted DBPs tended to be more toxic than chlorinated analogues. No zebrafish development effects were observed after exposure to undiluted or non-concentrated, chlorinated wastewater. We find zebrafish development to be a viable in vivo alternative or confirmatory assay to mammalian in vitro cell assays.

[Quantitative structure-activity relationship prediction of carcinogenicity of N-nitroso compounds based on category approach and read-across]

Objective: New quantitative structure-activity relationship (QSAR) method was used to predict N-nitroso compounds (NOCs) carcinogenicity. This could provide evidences for health risk assessment of the chemicals. Methods: Total 74 chemical substances of NOCs were included as target chemicals for this validation study by using QSAR Toolbox based on category approach and read-across. The included 74 NOCs were categorized and subcategorized respectively using "Organic functional groups, Norbert Haider " profiler and "DNA binding by OASIS V.1.1" profiler. Carcinogenicity of rat were used as target of prediction, the carcinogenicity results: of analogues in chemical categories were cross-read to obtain the carcinogenic predictive results of the target chemicals. Results 74 NOCs included 26 nonclic N-nitrosamines, 24 cyclic N-nitrosamines and 24 N-nitrosamides The sensitivity, specificity and concordance of the category approach and read-across for predicting carcinogenicity of 74 NOCs were 75% (48/64), 70%(7/10) and 74% (55/74) respectively. The concordance for noncyclic N-nitrosamines, cyclic N-nitrosamines and N-nitrosamides were 88% (23/26), 71% (17/24) and 63% (15/24) respectively. Conclusion: QSAR based on category approach and read-across is good for prediction of NOCs carcinogenicity, and can be used for high-throughput qualitative prediction of NOCs carcinogenicity.

Nitrosamine Formation in Amine-Based CO2 Capture in the Absence of NO2: Molecular Modeling and Experimental Validation

A computational chemistry approach was used to elucidate and verify the different nitrosamine formation mechanisms and pathways. These included nitrosamine formation under acid or basic environments in the presence of NO, O₂, SO₂ and CO₂ without NO₂. The results clearly showed that nitrosamine could be formed without NO₂ via 2 different types of mechanisms, namely, addition and elimination forming N-N bond before proton transfer and proton transfer before N-N bond formation, respectively. The essence of these mechanisms identified in this work was that two reaction steps were required to complete both reaction mechanisms with different nitrosating agents. Two steps were both necessary neither of which could be neglected, if the nitrosamine formation reaction was to be completed. Computational simulation performed on the reactant, intermediate, transition state, and product for each set of reactions also validated the proposed mechanisms. Experiment also detected nitrosamine from the reaction of diethylamine and NO, SO₂, O₂, and CO₂ in both liquid and gas phase. Thus, NO₂ is not necessary for nitrosamine formation to occur in the CO₂ capture system.

Role of membrane fouling substances on the rejection of N-nitrosamines by reverse osmosis

The impact of fouling substances on the rejection of four N-nitrosamines by a reverse osmosis (RO) membrane was evaluated by characterizing individual organic fractions in a secondary wastewater effluent and deploying a novel high-performance liquid chromatography-photochemical reaction-chemiluminescence (HPLC-PR-CL) analytical technique. The HPLC-PR-CL analytical technique allowed for a systematic examination of the correlation between the fouling level and the permeation of N-nitrosamines in the secondary wastewater effluent and synthetic wastewaters through an RO membrane. Membrane fouling caused by the secondary wastewater effluent led to a notable decrease in the permeation of N-nitrosodimethylamine (NDMA) while a smaller but nevertheless discernible decrease in the permeation of N-nitrosomethylethylamine (NMEA), N-nitrosopyrrolidine (NPYR) and N-nitrosomorpholine (NMOR) was also observed. Fluorescence spectrometry analysis revealed that major foulants in the secondary wastewater effluent were humic and fulvic acid-like substances. Analysis using the size exclusion chromatography technique also identified polysaccharides and proteins as additional fouling substances. Thus, further examination was conducted using solutions containing model foulants (i.e., sodium alginate, bovine serum albumin, humic acid and two fulvic acids). Similar to the secondary wastewater effluent, membrane fouling with fulvic acid solutions resulted in a decrease in N-nitrosamine permeation. In contrast, membrane fouling with the other model foulants resulted in a negligible impact on N-nitrosamine permeation. Overall, these results suggest that the impact of fouling on the permeation of N-nitrosamines by RO is governed by specific small organic fractions (e.g. fulvic acid-like organics) in the secondary wastewater effluent.

Effect of Ozonation and Biological Activated Carbon Treatment of Wastewater Effluents on Formation of N-nitrosamines and Halogenated Disinfection Byproducts

Ozonation followed by biological activated carbon (O₃/BAC) is being considered as a key component of reverse osmosis-free advanced treatment trains for potable wastewater reuse. Using a laboratory-scale O₃/BAC system treating two nitrified wastewater effluents, this study characterized the effect of different ozone dosages (0-1.0 mg O₃/mg dissolved organic carbon) and BAC empty bed contact times (EBCT; 15-60 min) on the formation after chlorination or chloramination of 35 regulated and unregulated halogenated disinfection byproducts (DBPs), 8 N-nitrosamines, and bromate. DBP concentrations were remarkably similar between the two wastewaters across O₃/BAC conditions. Ozonation increased bromate, TCNM, and N-nitrosodimethylamine, but ozonation was less significant for other DBPs. DBP formation generally decreased significantly with BAC treatment at 15 min EBCT, but little further reduction was observed at higher EBCT where low dissolved oxygen concentrations may have limited biological activity. The O₃/BAC-treated wastewaters met regulatory levels for trihalomethanes (THMs), haloacetic acids (HAAs), and bromate, although N-nitrosodimethylamine exceeded the California Notification Level in one case. Regulated THMs and HAAs dominated by mass. When DBP concentrations were weighted by measures of their toxic potencies, unregulated haloacetonitriles, haloacetaldehydes, and haloacetamides dominated. Assuming toxicity is additive, the calculated DBP-associated toxicity of the O₃/BAC-treated chloraminated effluents were comparable or slightly higher than those calculated in a recent evaluation of Full Advanced Treatment trains incorporating reverse osmosis.

Relative Importance of Different Water Categories as Sources of N-Nitrosamine Precursors

A comparison of loadings of N-nitrosamines and their precursors from different source water categories is needed to design effective source water blending strategies. Previous research using Formation Potential (FP) chloramination protocols (high dose and prolonged contact times) raised concerns about precursor loadings from various source water categories, but differences in the protocols employed rendered comparisons difficult. In this study, we applied Uniform Formation Condition (UFC) chloramination and ozonation protocols mimicking typical disinfection practice to compare loadings of ambient specific and total N-nitrosamines as well as chloramine-reactive and ozone-reactive precursors in 47 samples, including 6 pristine headwaters, 16 eutrophic waters, 4 agricultural runoff samples, 9 stormwater runoff samples, and 12 municipal wastewater effluents. N-Nitrosodimethylamine (NDMA) formation from UFC and FP chloramination protocols did not correlate, with NDMA FP often being significant in samples where no NDMA formed under UFC conditions. N-Nitrosamines and their precursors were negligible in pristine headwaters. Conventional, and to a lesser degree, nutrient removal wastewater effluents were the dominant source of NDMA and its chloramine- and ozone-reactive precursors. While wastewater effluents were dominant sources of TONO and their precursors, algal blooms, and to a lesser degree agricultural or stormwater runoff, could be important where they affect a major fraction of the water supply.

Full Advanced Treatment trains for potable reuse

Water utilities are increasingly considering indirect and direct potable reuse of municipal wastewater effluents. Disinfection byproducts (DBPs), particularly N-nitrosamines, are key contaminants of potential health concern for potable reuse. This study quantified the concentrations of N-nitrosamines and a suite of regulated and unregulated halogenated DBPs across five U.S. potable reuse Full Advanced Treatment trains incorporating microfiltration, reverse osmosis, and UV-based advanced oxidation. Low μg/L concentrations of trihalomethanes, haloacetic acids, dichloroacetonitrile, and dichloroacetamide were detected in the secondary or tertiary wastewater effluents serving as influents to potable reuse treatment trains, while the concentrations of N-nitrosamines were more variable (e.g., <2-320 ng/L for N-nitrosodimethylamine). Ozonation promoted the formation of N-nitrosamines, haloacetaldehydes, and haloacetamides, but biological activated carbon effectively reduced concentrations of these DBPs. Application of chloramines upstream of microfiltration for biofouling control increased DBP concentrations to their highest levels observed along the treatment trains. Reverse osmosis rejected DBPs to varying degrees, ranging from low for some (e.g., N-nitrosamines, trihalomethanes, and haloacetonitriles) to high for other DBPs. UV-based advanced oxidation eliminated N-nitrosamines, but only partially removed halogenated DBPs. Chloramination of the treatment train product waters under simulated distribution system conditions formed additional DBPs, with concentrations often equaling or exceeding those in the treatment train influents. Overall, the concentration profiles of DBPs were fairly consistent within individual treatment trains for sampling campaigns separated by months and across different treatment trains for the same sampling time window. Weighting DBP concentrations by their toxic potencies highlighted the potential significance of haloacetonitriles, which were not effectively removed by reverse osmosis and advanced oxidation, to the DBP-associated toxicity in potable reuse waters.

Occurrence of nitrosamines and their precursors in drinking water systems around mainland China

N-Nitrosamines (NAs) in drinking water have attracted considerable attention in recent years due to their high carcinogenicity, frequent occurrence, and their potential regulation. During the past three years, we have collected about 164 water samples of finished water, tap water, and source water from 23 provinces, 44 cities from large cities to small towns, and 155 sampling points all over China. The occurrence of NAs in the finished and tap water was much higher in China than that in the U.S. Nine NAs were measured and NDMA had the highest concentration. The occurrence of NDMA was in 33% of the finished waters of water treatment plants and in 41% of the tap waters. The average NDMA concentration in finished and tap waters was 11 and 13 ng/L, respectively. Formation potentials (FPs) of source waters were examined with an average NDMA FP of 66 ng/L. Large variations in NA occurrence were observed geographically in China and temporally in different seasons. The Yangtze River Delta area, one sub-area in East China, had the highest concentrations of NAs, where the average NDMA concentrations in the finished and tap water were 27 and 28.5 ng/L, respectively, and the average NDMA FP in the source water was 204 ng/L. NA control may be achieved by applying breakpoint free chlorination and/or advanced treatment of ozone - granular activated carbon process to remove the NA precursors before disinfection.

Modelling atmospheric oxidation of 2-aminoethanol (MEA) emitted from post-combustion capture using WRF-Chem

Carbon capture and storage (CCS) is a technological solution that can reduce the amount of carbon dioxide (CO2) emissions from the use of fossil fuel in power plants and other industries. A leading method today is amine based post-combustion capture, in which 2-aminoethanol (MEA) is one of the most studied absorption solvents. In this process, amines are released to the atmosphere through evaporation and entrainment from the CO2 absorber column. Modelling is a key instrument for simulating the atmospheric dispersion and chemical transformation of MEA, and for projections of ground-level air concentrations and deposition rates. In this study, the Weather Research and Forecasting model inline coupled with chemistry, WRF-Chem, was applied to quantify the impact of using a comprehensive MEA photo-oxidation sequence compared to using a simplified MEA scheme. Main discrepancies were found for iminoethanol (roughly doubled in the detailed scheme) and 2-nitro aminoethanol, short MEA-nitramine (reduced by factor of two in the detailed scheme). The study indicates that MEA emissions from a full-scale capture plant can modify regional background levels of isocyanic acid. Predicted atmospheric concentrations of isocyanic acid were however below the limit value of 1 ppbv for ambient exposure. The dependence of the formation of hazardous compounds in the OH-initiated oxidation of MEA on ambient level of nitrogen oxides (NOx) was studied in a scenario without NOx emissions from a refinery area in the vicinity of the capture plant. Hourly MEA-nitramine peak concentrations higher than 40 pg m(-3) did only occur when NOx mixing ratios were above 2 ppbv. Therefore, the spatial variability and temporal variability of levels of OH and NOx need to be taken into account in the health risk assessment. The health risk due to direct emissions of nitrosamines and nitramines from full-scale CO2 capture should be investigated in future studies.

Inhibitory effect of 5F on development of lung cancer in A/J mice

The purpose of the study is to investigate the effect of ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F) on the model of induced A/J mice lung cancer in A/J mice. The expressions of tumor-related molecules including P65 and Bcl-2 at protein level were examined using the immunohistochemical method (IHC). Side effects of 5F were also monitored. The results indicated that 5F significantly suppressed the development of B[a]P and NNK-induced lung cancer in vivo by facilitating cell apoptosis with minimal side effects. Compared to the expressions of P65 and Bcl-2 in model group, the levels were strongly attenuated both in blank and 5F injection groups. Moreover, P65 and Bcl-2 levels varied among different groups receiving 5F treatment. The expressions of P65 and Bcl-2 were much lower in groups receiving high-concentration 5F treatment than those with low-concentration 5F injection. Findings revealed that 5F inhibited the pathogenesis of lung cancer through accelerating apoptosis in a dose-dependent manner.

Public education about the relative harm of tobacco products: an intervention for tobacco control professionals

BACKGROUND

In the USA, new regulations require the collection of information on tobacco constituents by brand and variety and publication of this information in a way not likely to be misconstrued by consumers. Understanding of such information becomes increasingly important as new tobacco products are marketed and modifications are made to reduce the toxicity of some products. This pilot study assessed the current knowledge of tobacco control professionals regarding the relative harmfulness of several tobacco products, and evaluated an online educational intervention aimed at improving understanding of variations in nicotine and tobacco-specific N-nitrosamines (TSNAs).

METHODS

Fifty-two tobacco control professionals participated in an online intervention which presented and discussed the results of constituent analyses of Camel Snus and Marlboro Snus compared to several conventional smokeless tobacco products. Comparisons with cigarettes were also discussed. Pre- and post-intervention questions assessed understanding of the concepts.

RESULTS

Pre-intervention responses demonstrated that 31% did not know that cigarettes are more harmful than smokeless tobacco, 67% did not know that smokeless products higher in nicotine are likely to be more effective substitutes for cigarettes, 52% did not know TSNAs are the major carcinogens in tobacco and 81% did not know new snus products tend to be lower in TSNAs than conventional spit tobacco. After intervention participation, knowledge increased on all points except one where pretest results were 100% correct.

CONCLUSIONS

Public education campaigns are urgently needed for tobacco control professionals and consumers to increase awareness and understanding of the continuum of risk among tobacco products.

Chemopreventive effects of the p53-modulating agents CP-31398 and Prima-1 in tobacco carcinogen-induced lung tumorigenesis in A/J mice

Lung cancer is the leading cause of cancer deaths worldwide. Expression of the p53 tumor suppressor protein is frequently altered in tobacco-associated lung cancers. We studied chemopreventive effects of p53-modulating agents, namely, CP-31398 and Prima-1, on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung adenoma and adenocarcinoma formation in female A/J mice. Seven-week-old mice were treated with a single dose of NNK (10 µmol/mouse) by intraperitoneal injection and, 3 weeks later, were randomized to mice fed a control diet or experimental diets containing 50 or 100 ppm CP-31398 or 150 or 300 ppm Prima-1 for either 17 weeks (10 mice/group) or 34 weeks (15 mice/group) to assess the efficacy against lung adenoma and adenocarcinoma. Dietary feeding of 50 or 100 ppm CP-31398 significantly suppressed (P < .0001) lung adenocarcinoma by 64% and 73%, respectively, after 17 weeks and by 47% and 56%, respectively, after 34 weeks. Similarly, 150 or 300 ppm Prima-1 significantly suppressed (P < .0001) lung adenocarcinoma formation by 56% and 62%, respectively, after 17 weeks and 39% and 56%, respectively, after 34 weeks. Importantly, these results suggest that both p53 modulators cause a delay in the progression of adenoma to adenocarcinoma. Immunohistochemical analysis of lung tumors from mice exposed to p53-modulating agents showed a significantly reduced tumor cell proliferation and increased accumulation of wild-type p53 in the nucleus. An increase in p21- and apoptotic-positive cells was also observed in lung tumors of mice exposed to p53-modulating agents. These results support a chemopreventive role of p53-modulating agents in tobacco carcinogen-induced lung adenocarcinoma formation.